Head rests for vehicle seats in motor vehicles are primarily intended to protect those travelling in the vehicle, particularly when being hit from behind. Rear vehicle seats, but also front seats, are often foldable in order to make the cargo space of the vehicle flexible. In order to achieve this, the back rest is foldable towards the seat so that it will not come into conflict with surfaces in front or below in the vehicle, for example seats in front. It is previously known to adjust the neck rest to a position to a position which needs less space by means of a link system which, when folding the back rest pulls the head rest towards the upper edge of the back rest, see WO 94/01302. This solution, however, obtains a more limited decreasing of the space when folded. Also, for other purposes such as the view rearwards, there can be reasons for temporarily adjusting the head rest.